In a statement released by the team Monday, Predators general manager David Poile said Fisher underwent surgery Thursday after rupturing the tendon during a training session.
''We expect Mike to make a full recovery in four to six months, and look forward to his return to the ice,'' Poile said.
The Predators open the season Oct. 9 against Ottawa.
Fisher, 34, served as Nashville's alternate captain last season and had 20 goals and 29 assists in 75 games. He has 226 goals and 255 assists in 887 career regular-season games.
Fisher tweeted, ''Setbacks are opportunities for growth,'' on Monday and included a picture of his bandaged lower leg in a walking boot.
The injury seriously hinders Nashville's plans to boost its offense under new coach Peter Laviolette.
After missing the playoffs for a second straight season, Poile fired coach Barry Trotz and replaced him with Laviolette, emphasizing the need to add more scoring punch to a franchise that traditionally has prided itself on defense.
The Predators have spent much of the offseason attempting to boost that offense. They acquired forward James Neal from the Pittsburgh Penguins and signed free-agent center Olli Jokinen to a one-year, $2.5 million contract.
But the Predators would suffer a major blow if they have to spend much of the season without Fisher, one of the team's top offensive threats since coming to Nashville in a 2011 trade with the Ottawa Senators.
Monday's news continues the Predators' recent run of bad luck with injuries to key players. Star goaltender Pekka Rinne played just 24 games last season because of an E. coli infection in his surgically repaired left hip. Rinne's injury may have cost the Predators a playoff berth, as they finished the season three points out of eighth place in the Western Conference.